#    Copyright 2013 Mirantis, Inc.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

from stevedore import extension


_PLUGIN_MANAGER = None


def get_plugin(plugin):
    global _PLUGIN_MANAGER
    plugin_manager = _PLUGIN_MANAGER

    if plugin_manager is None:
        PLUGINS_NAMESPACE = 'plugins'
        plugin_manager = extension.ExtensionManager(PLUGINS_NAMESPACE,
                                                    invoke_on_load=True)

    _PLUGIN_MANAGER = plugin_manager
    return _PLUGIN_MANAGER[plugin].obj
